Switch mechanism



Jan. 21, 1941.

A. L. JUDSON swf'rca magmmxsu Filed JanwlIS, 1938 2 $heets-Sheet 1 INVENTOR Albert I4. Judson ATTORNEY Jan. 21, 1941.

A. L. JUDSON SWITCH MECHANISM Filed Jan. 13, 1938 2 Sheets-Sheet 2 INVENTOR v Albert L.Judson ATTORNEY I Patented Jan. 21, 1941 i I UNITED STATES PATENT OFFICE swrrcn MECHANISM Albert L. Judson, Minneapolis, Minn assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application January 13, 1938, Serial No. 184,812 9 Claims. (01. zoo-s3) This invention relates broadly to a switching shown in Figure 1 showing the switch operating mechanism and more particularly to a snap actlever in closed circuit position; ing switch which is operated in response to some Figure 3 is a side elevation showing the snap condition such as temperature or pressure to action mechanism, being partly in section taken open or close a set of contacts. For purposes of on the line 33 of Figure 2; 5

illustration only, the device will be described as Figures 4 and 5 are detail views more or less being responsive to pressure, but it is to-be disdiagrammatic showing two operating positions of tinctly understood that it may just as easily be the snap action mechanism;

made to respond to temperature. Figure 6 is a perspective view of the main op- An object of this invention is to provide a crating lever; 1

switch having reversible contacts so that it will Figure 7 is a perspective view of the bail; open or close its contacts when the pressure to u e 8 s a sect on ta en o e 8 of Figwhich it responds reaches a predetermined point, ure 2 showing the reversible switch mounting; depending upon the position in which they have and 0 been placed. Figure 9 is a perspective view of the reset and A further object is to provide a pressure redifl'erential adjusting lever. sponsive switch which may be adapted to break The present device is provided with a base plate the circuit to' an operating device upon the oc- II to t e bottom f w h is attached a casing currence of a high pressure which indicates a I! by suitable means such as screws I3 and I4. dangerous condition in said device. Within casing l2 is a pressure responsive device 20 A further object of th invention i to provide such as a'bellows (not shown). Depending from a high pressure cut-out switch which will autohe l wer p r i n f in 2 is a nipp e l5 matically return to closed circuit position upon a adapted for connection to a source of pressure to drop in pressure to a value which is below that be controlled or it the deviceis intended to re- 35 which caused switch opening. spond to temperature changes it may be con- Another object is to provide; a snap action nected to a thermal bulb by means of capillary mechanism operated by a condition responsive tubing. Mounted on the upper face of base ll device for opening a switch, with additional e o up din Supporting brackets 16 and means also operated by said condition responsive 11, these brackets are mounted on the base plate no mechanism for positively openin d it h n by a suitable means such as screws I8 and I9 and case said snap acting mechanism should fail for r connected ar heir top by means of a plate some reason, 20 having bifurcations 2| and 22 at each end.

A still further object is to provide a high preswhich are inserted in holes 23 and 24 of the ur switch which will out o t at high pressure brackets. Positioned between these brackets and 5 and t in again wh n th pressure drops t pivoted thereto as at 25'and'26 is a pair of jawpredetermined lower value and which has a sh ped l v 21 having horizontally xt n in means for adjusting this difierentigi, Y lower portions 28 integrally connected together Another object of this invention is to Provide by cross Piece Pivted the upper P Of a switch which will cut out at a high pressure and this lever at 29 is a D c a e member which will attempt to close at a predetermined 30 having a supporting base portion 3| in which 40 lower pressure but which has a stop for preventis Seated a main adjusting Spring tending ing such return, and a manual means for reset- 1005613 through a hole in connecting P e 20 s ting the switch to closed position after it has once scl'ew 33 hill/mg head 34 and a screw threaded t t. 7 stem 35. Securely fastened to said stem and po- Still another object is to provide a switch of sltioned immediately underneath n ting 45 the above character which has a single lever P e 20 s a Washer 35 which Prevents p a d. i h is adapted t act as an j t t for the movement of said screw. Threaded on said stem differential of the switch or as a manual reset is a nut Carrying a horizontally l pOrafter th it h h opened 'tion 38 which coacts with the sides of supporting 53 Other objects will become apparent upon a, brackets l6 and I! to prevent rotation of the study of the description of the device in connec- 111117 119011 rotation of e screwp ing 32- is tion with the accompanying drawings in which: co p essed between the PP rting base 3| of the Figure 1 is a side elevation of one embodiment carriage 30 and the non-rotatable nut 31 By of my invention; rotating screw 33, nut 31 may be adjusted ver- Figure 2 is a front elevation of the device tically thereby adjusting the degree of compresa,

sion of, and hence the force exerted by spring 32. Secured underneath the base portion 3| of the carriage 30 is a bearing member 39 having a dwell therein in which seats a pin 48 which is connected to the pressure responsive device in casing I2. Spring 32 therefore opposes upward movement of pin 40 by the bellows and adjustment of screw 33 will adjust spring 32 and hence vary the main pressure setting of the device. I

Each of the lower portions of the jaw-shaped levers 21 has a dwell therein as shown at 4| and 42 in which are seated legs of bail member which legs are in the form of knife edges. As better shown in Figure 7 bail member 45 is provided with lugs 44 which are adapted to fit under the extensions 65, shown in Figure 6, on lower portions 28 of levers 21. This construction will prevent bail 45 from jumping out of the dwells 4| and 42. Hooked through a hole 46 in the top of ball 45 is one end of a spring member 41, the lower end of which is looped over a rod 48 which connects two legs 49 and 50 of a lever 5|. This lever is pivoted .to the supporting brackets I6 and IT at 52 and 53 and carries at its upper end two sets of movable switch contacts 54 and 55 which are connected thereto by means of screws 56 and 51. The con- .tact members 54 and 55 are'resiliently seated in casings 58 and 59 thus assuring a positive seating when the switches are closed. Supporting brackets I6 and H are provided with a pair of cars 60 to which is attached an insulating base 6| by means of screws 62 and 63. The insulating base carries a. series of stationary contacts 64 for cooperation with the .two pair of movable contacts 54 and 55. It will "be noted that the insulated base carries insulating walls 66, 61 and 68 between each of the stationary contacts. Extending inwardly from each of the supporting brackets I6 and I1 are arms 69 and 18 which form a stop for bail "member 45 as it is rotated in a clockwise direction. Arm 12 forms a stop for the bail as it is rotated in a counter-clockwise direction which arm and its supporting structure will be described later.

Referring to Figure 3 it will be seen that contact carrying lever 5| is pivoted at 52 and 53, and that spring 41 being tensioned between bail member 45 and nod 48 in lever 5| is tending to rotate the lever in a counter-clockwise direction. When the ball is rotated in a counter-clockwise direction by levers 21 the upper end of the spring 41 will snap to the leftwhich will bring the line of force of the spring on the other side of the pivots 52 and 53. Thus we see in Figure 4 that when this has occurred the force of spring 41 will rotate the lever 5| in a clockwise direction causing the switch contacts to open. The effect of this spring 41 as it passes over center is to open these switch contacts with a, SIIBJP action. Returning again to Figure 3 it will be seen that spring 41 is tending to rotate bail 45 in a clockwise direction. As the lower end 28 of lever 21 moves to the'right it carries with it the lower end of bail 45 and upon continued movement in this direction willcause this lower end to pass beyond the present line of force of sprlng 41. This will cause the spring to rotate bail 45 in a counter-clockwise direction and take up the position shown in Figure 4, which will occur with a snap action due to spring 41. Thus it will be seen that two distinct snap actions take place, first upon movement to the right of the lower part 28 of levers 21 the bail member 45 will snap in a counter-clockwise direction, which movement will cause spring 41 to align itself on the opposite side of the pivot pins 52 and 53 of the contact carrying lever causing it to snap in a clockwise direction.

Carried by the lower portion of levers 21 on the side opposite'lever 16 is an arm 88 having a bent-in portion 89 for cooperation with casing 58. This is-for the purpose of providing a means for positively actuating the switch contacts in case the snap action mechanism should fail. If on a pressure increase the snap action mechanism should fail to operate, portion '89 will engage the casing 58 and positively open the contacts.

As better seen in Figure 3- the stationary contacts 64 are supported by means of brackets 98 mounted on insulation 6| by means of screws 92 screwed in bushings 3| in the insulation 6|. Referring to Figure 8 it will be seen that contact member 55 is secured to a block of insulating material 93 by means of pin 94. The block 93 is seated in' a cup-shaped member 95 and is resiliently maintained in place by means of spring 96 and screw 51. Thus a good contact is assured on closing movement of the contact carrying lever.

One of the features of this invention is that the position of the contacts may :be reversed so that the circuit will be made on an increase in pressure. This is accomplished by removing screws 92 and reversing the position of brackets 98 so that the contacts 64 face in the other direction. It will be seen in Figure 8 that screw 51 may be removed and block 93 and spring 36 reversed in cup 95 and then screwed together again by screw 51. With the contacts so arranged the circuit will be broken when the contact carrying lever is in the position shown in Figure 3, and made when it is in the position shown in Figure 4.

Lever 5| has 'at the lower portion thereof an extension 13 having a cut-away portion 14. Pivoted at 15 on supporting bracket I1 is a lever 16, shown in detail in Figure 9, having an arm 11 with a horizontally and inwardly extending portion 18 which is adapted to cooperate with the shoulder formed by the cut-away portion 14 of lever 5|. A spring 19 has an end 88 which is inserted underneath a portion of supporting bracket I1 and carried about pivot stem 15 for the lever 16 and whose other end 8| is hooked under arm 82 of lever 16 to bias it for rotation in a counter-clockwise direction. The above structure is for the purpose of providing a manual reset for the switch. A V-shaped slot 11a is provided in arm 11 so that if the manual reset feature is not desired arm 11 may be broken off.

Screwed into an ear 83 of the supporting bracket I1 is a screw 84 having a locknut 85. The end of this screw is positioned above arm 82 01 the lever 16 to limit the amount of its counterclockwise rotation produced by the spring 19. It will be noted that this lever 16 has a horizontal arm 86 which has an inwardly extending portion forming the stop 12 for bail 45. A djustment of screw 84 in and out of ear 8.3 will therefore adjust the position of stop 12 which, as will be explained later, varies the difi'erential of the device. This feature is used only when the manual reset feature is not desired and arm 11 must be broken ofi in order to make the differential adjustment feature operative. This is because the engagement of arm 11 with extension 13 will determine .the position of the lever 16 unless arm 11 is removed.

Operation The operation will 'iirst be described in connection with the manualreset feature, it being understood that at this time the screw 84 is omitted. Assuming the parts to be in the position shown in Figures 1, 2, and 3, it is noted that the lever 21 has been rotated to its clockwise position and the double snap action mechanism has produced closure or the switch contacts. 'Iever- 15 is prevented by a portion of extension 13 from being rotated by spring 15 further in a. counter-' its pivots 25-25. This in turn will cause its lower end 28 to move to the right snapping the ball '45 in a counter-clockwise direction as explained above which will cause the spring 41 to snap lever in a clockwise direction until legs 49 and 50 strike base member Ii. This causes the switch contacts to open. As the lever 5| snaps to its open contact position it'raises its extending portion 13 whlch'permits spring 19 to rotate lever 16 in a counter-clockwise direction until arm 11 engages the shoulder formed by the cut-away portion 14. Thus on an increase of pressure to the point for which the device has been adjusted by screw 34, the parts will snap over from the position shown in Figures 1, 2, and 3 to that shown in Figure 4. Arm I2 on lever 16 is acting as a stop for the top of bail 45 and is limiting the amount of its counter-clockwise rotation. As set forth above base member ii is limiting the clockwise rotation of lever 5|.

The switch contacts are now open and the pressure begins to decrease. Operating pin 40 will be lowered allowing spring 32 to depress care riage 30 and rotate lever 21 in a counter-clockwise direction. This causes the lower end 2t 01 lever 21 to move generally to the left carrying with it the lower end of the bail which will eventually pass beyond the line of force of spring 41 causing ball 45 to snap to its clockwise position. This will move the line of force of spring 41 on the other side of pivot 52-43 of lever 5i which will cause the lever to rotate in a counter-clockwise direction as shown in Figure 5. It will be noted however that the shoulder formed by the cut-away portion 14 on extension 13 engages por tion 18 of arm TI on lever '15 and thus prevents lever 5| from rotating far enough to close the switch contacts. The only way the switch may now be closed is by manually depressing arm 82 of lever 85 which will remove portion ll from engagement with the shoulder 14 and permit spring 41 to complete the counter-clockwise rotation of lever 5|and close the switch contacts. The parts have now returned to the position shown in Figures 1, 2, and 3 and the switch is ready to be opened again should the pressure increase to thepoint for which the device is adjusted.

In some instances it may be desired to have a switch which is completely automatic, that is, one 7 the breakage of spring 41.

might be dangerous it the switch was not opened to prevent the complete return of lever 5| to switch closed position by the snap action mechanism. In a device of this type it may be desirable to have an adjustable differential tor the snap action mechanism so that the pressure at which the switch will closemay be adjusted. This adjustment is accomplished by means of screw 54.

Assume for example that the device is adjusted so that the switch contacts are snapped open at a pressure of 180 pounds. The parts will now be in the position shown in Figure 4 with the bail 45 resting against the stop arm 12 of lever 16. As the switch contacts are open at this time the pressure will begin to drop which will cause the lower end 28 of lever 21 to move generally to the left. At a pressure oi say 160 pounds the lower end of the ball will have moved beyond the line of force of spring 41 and the switch will snap shut, it being remembered that arms I1 and 18 have been removed from lever 15 so that nothing prevents the complete operation of lever Si by the snap action mechanism.

The lower the arm 12 is positioned'the greater the angle between the bail 45 and the spring 41 as viewed in Figure 4 and hence the greater the eflect of the force exerted by spring 41 tending to rotate the bail in a counter-clockwise direction. This means that the pressure in the bellows must drop lower, say to 140 pounds, to permit the main spring 32 to develop a force strong enough to swing levers 21 to the left and cause ball 45 to snap over center. As set forth above the position of arm 12 is determined by screw 84 which therefore determines the. difierential oi the device. The lower the arm 12 is positioned the greater will be the operating differential.

If it is desired to produce a switch which will close on high pressure it is necessary only to reverse the position of both the stationary and movable switch contacts as described above. In this case the manual reset will act to maintain the switch closed until manually opened. The diflerential adjustment will work the sameexcept that it will determine the pressure at which the switch breaks instead of the pressure at which it makes.

It might occur sometimes that the snap action mechanism would fail for some reason such as In such a case it upon the occurrence. of a high pressure. For this reason I have provided the arm 85 on lever 21 which'ii the snap action mechanism should fail to work would strike the contact carrier 58 and positively move the switch to open position.

Many changes and modifications of this invention will occur to those who are skilled in the art and therefore it is to be distinctly understood that I am not to be limited by the illustration and description of this particular embodiment but rather by the scope of the appended claims.

The present switching device is of the same general type as the one disclosed by Carl G. Kronmiller in application Serial No. 184,811 filed concurrently herewith.

The expression double snap action mechanism as used in the claims is intended to cover any mechanism wherein one element snaps and either directly or indirectly causes a second element to snap.

I claim as my invention:

1. In a control device of the character described. a control member, a condition responsive device, a spring, means operated by said condition responsive device against the action of said spring, said means operating a double snap action mechanism comprising a bail having two stops and coacting at one end with said means and being connected at the other end with one end of an over-center spring, said spring being connected at its other end to said control member, a lever pivoted intermediate its ends to a stationary support, a spring tending to rotate said lever in one direction, stop means cooperating with one arm of said lever to limit such rotation, the other arm forming one of the stops for said bail, and. means for adjusting the position of said lever and hence the diiferential of the snap action mechanism.

2. In a control device of the character described, a control member, a condition responsive device, a spring, means operated by said condition responsive device against the action of said spring, said means operating a double snap acting mechanism comprising a bail having two stops and coacting at one end with said means and being connected at the other with one end of an over-center spring, said spring being connected at its other end to said control member, a lever pivoted intermediate its ends to a stationary support, one arm of said lever forming one of the stops for said bail, an adjustable screw, and a spring holding the other end of said leveragainst said adjustable screw, adjustment of said screw adjusting the differential of said snap acting mechanism.

3. In a control device of the character described, a control member, a condition responsive device, a spring, a lever operated by said cond tion responsive device against the action of said spring, said lever operating a double snap acting mechanism comprising a bail having two stops and coacting at one end with said lever and being connected at the other with one end of an overcenter spring, said spring being connected at its other end to said control member, a second lever pivoted intermediate its ends to a stationary support, a spring tending to rotate said lever in one a direction, stop means cooperating with one of said levers to limit such rotation, the other arm forming one of the stops for said bail, and means for adjusting the position of said lever and hence the difierential of the snap action mechanism and means for adjusting said first mentioned spring to adjust the main setting of the control device.

4. In a control device of the character described, a double snap action mechanism including a bail having two stops, a condition responsive device for operating said snap action mechanism in one direction, a spring for operating said snap action mechanism in the other direction, a

pivoted control lever actuated by said snap action mechanism, a second pivoted lever having an arm, a projection on said control lever adapted to engage said arm to prevent actuation by said snap action mechanism under the influence of said spring, means for manually moving said arm to permit operation of said control lever by said snap action mechanism, means for breaking off said arm if it is not desired, a member on said lever forming one of the stops for said bail, and an adjustable means for positioning said stop member in order to adjust the differential of the device when said arm has been broken oil.

5. In a control device of the character described, a snap action mechanism, a condition responsive device for operating said snap action mechanism, a pivoted control lever actuated by said snap action mechanism, a second pivoted lever having three arms, one arm acting as a stop for preventing operation of said control lever in one direction by said snap action mechanism, a second arm providing a manual means for removing the stop for permitting such operation, means for removing said first arm-when it is not desired, a third arm cooperating with said snap action mechanism to determine the difi'erential of operation thereof, and means for adjusting said third arm, said means being operable only after said first arm has been removed.

6. In a pressure responsive switch, a double snap action mechanism including a bail having two stops, a condition responsive device for operating said snap action mechanism in one direction, a spring for operating said snap action mechanism in the other direction, a pivoted control lever carrying a movable contact, means for operating said control lever by said snap action mechanism, a stationary contact positioned for cooperation with said movable contact, a second pivoted lever having three arms, the first arm cooperating with said control lever to prevent its operation by said snap action mechanism under the influence of said spring, the second arm acting as a manual means for moving said first arm to permit such operation, means for removing said first arm from said lever if it is not desired, the third arm forming one of the stops for the bail and hence determining the operating differential of the snap action mechanism, and means for adjusting the position of said third arm, said last named means being inoperative except when-said first armhas been removed,

7. In a pressure responsive switch, a double snap action mechanism including a movable contact carrying lever and a bail having two stops, a condition responsive device for operating said snap action mechanism in one direction, a spring for operating said snap action mechanism in the other direction, a movable contact carried by said lever, a stationary contact positioned for cooperation with said movable contact, a second pivoted lever having three arms, means constantly tendmg to rotate said lever, the first arm cooperating with a portion of said contact carrying lever to prevent its operation in one direction, the second arm providing manual means for moving said first arm to permit such operation, said first arm having a notch cut therein so that it may be broken off if it is not desired, the third arm forming one of the stops for the bail, a fixed element having a screw threaded hole therethrough -located above said second arm, and a screw adapted to be threaded through said hole to limit the rotation of said second lever as produced by said spring when said first arm has been broken off, to adjustably position said third arm.

8. An electric switch comprising in combination, a lever, a first contact, means for resiliently mounting said contact on said lever including a piece of insulating material, said contact being mounted therein, a spring located adjacent said insulation, retaining means for maintaining the parts in assembled relation, said insulation and spring being reversible with respect to said lever and retaining means, a second contact mounted at one side of said first contact on a stationary support, and merns for mounting said second contact on the opposite side of said'first contact.

9. In a device of the character described comprising in combination, a double snap action mechanism including a bail, a pivoted control member, a tension spring connecting one end of said bail to said control member, condition responsive means for moving the other end of said bail on variations in said condition; a. spring pressed stop member positioned to cooperate with said control member in such a. manner that on a variation in said condition in one direction said condition responsive means will move said bail which will in turn snap said control member from a first position to a second position, and on a variation in said condition in the opposite direction said condition responsive means will move 

